The speed of zooming operation of a taking lens used in a television camera for broadcasting purpose is usually controlled with use of a controller for speed control purpose. For instance, a rotatable thumb ring is provided on a controller (an operating apparatus) for speed control purpose called a zoom demand. During a non-operating state in which the thumb ring is not operated, the taking lens automatically returns to a reference position. When the thumb ring is rotatably operated from that reference position, the taking lens is zoomed in accordance with the speed corresponding to the amount of rotational operation. In order to facilitate operation required to effect zooming operation at a low speed during such a zooming speed control operation, there is employed a technique for changing the zooming speed in a non-linear manner in response to the amount of operation of the operating section, such as the thumb ring (see, e.g., Japanese Patent No. 2,810,437).
There are many cases where a controller equipped with an operating section, such as a thumb ring, and a lens controller for effecting lens control, such as zoom control operation, in response to a control signal output from a controller in accordance with operation of the operating section are commercialized in the form of separate apparatus. Many lens controllers are integrated with a taking lens (an optical system) Currently, there mixedly exist a controller (generally used for controlling a high-grade lens) which has a non-linear characteristic and outputs a control signal whose value changes in a non-linear manner with respect to the amount of operation of the operating section set forth; and a controller which has a linear characteristic and outputs a control signal (a linear control signal) whose value changes linearly with respect to the amount of operation.
Meanwhile, the lens controller is also in the same circumstance as that of the controller. There mixedly exist a lens controller which has a non-linear characteristic and performs non-linear control operation by converting the control signal output from the controller into a non-linear control signal; and a lens controller which has a linear characteristic and performs linear control operation by using the control signal output from the controller while maintaining the characteristics of the control signal unchanged.
Therefore, there may be a case where the lens controller and the controller each have non-linear characteristics, depending on a combination thereof. In this case, there arises a problem of the non-linear effect becoming excessive, which in turn deteriorates operability.
There may also be a case where a television camera is mounted on a pan head of a pan-head system and where the zooming position, or the like, of a taking lens of the television camera is controlled through use of a controller of the pan-head system. In such a case, if a lens controller having a non-linear characteristic is incorporated in the system and there is performed processing for converting the control signal given to the lens controller into a non-linear control signal, there may arise a problem in positional accuracy or operability.